The newborn planet population emerging from ring-like structures in discs

ALMA has observed a plethora of ring-like structures in planet forming discs at distances of 10-100 au from their host star. Although several mechanisms have been invoked to explain the origin of such rings, a common explanation is that they trace new-born planets. Under the planetary hypothesis, a natural question is how to reconcile the apparently high frequency of gap-carving planets at 10-100 au with the paucity of Jupiter mass planets observed around main sequence stars at those separations. Here, we provide an analysis of the new-born planet population emerging from observations of gaps in discs, under the assumption that the observed gaps are due to planets. We use a simple estimate of the planet mass based on the gap morphology, and apply it to a sample of gaps recently obtained by us in a survey of Taurus with ALMA. We also include additional data from recent published surveys, thus analysing the largest gap sample to date, for a total of 48 gaps. The properties of the purported planets occupy a distinctively different region of parameter space with respect to the known exo-planet population, currently not accessible through planet finding methods. Thus, no discrepancy in the mass and radius distribution of the two populations can be claimed at this stage. We show that the mass of the inferred planets conforms to the theoretically expected trend for the minimum planet mass needed to carve a dust gap. Finally, we estimate the separation and mass of the putative planets after accounting for migration and accretion, for a range of evolutionary times, finding a good match with the distribution of cold Jupiters

OBSERVATION OF SPIN ROTATION EFFECTS IN POLARIZED HE-3-HE-4 MIXTURES

Quantum exchange effects, predicted to occur in the spin diffusion of polarized nondegenerate gases, have been observed in a 3He-4He mixture by spin-echo techniques. Measurements of the spin rotation parameter (μM0)2 and diffusion constant D are in reasonable agreement with theoretical predictions until the degeneracy temperature is approached

OBSERVATION OF SPIN ROTATION EFFECTS IN POLARIZED HE-3-HE-4 MIXTURES

Quantum exchange effects, predicted to occur in the spin diffusion of polarized nondegenerate gases, have been observed in a 3He-4He mixture by spin-echo techniques. Measurements of the spin rotation parameter (μM0)2 and diffusion constant D are in reasonable agreement with theoretical predictions until the degeneracy temperature is approached

Plant signalling in symbiosis and immunity

Plants encounter a myriad of microorganisms, particularly at the root–soil interface, that can invade with detrimental or beneficial outcomes. Prevalent beneficial associations between plants and microorganisms include those that promote plant growth by facilitating the acquisition of limiting nutrients such as nitrogen and phosphorus. But while promoting such symbiotic relationships, plants must restrict the formation of pathogenic associations. Achieving this balance requires the perception of potential invading microorganisms through the signals that they produce, followed by the activation of either symbiotic responses that promote microbial colonization or immune responses that limit it